Mesh Stabilizer for Natural Draft Lean Premixed Burners
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Solution Overview
Problem
Lean premixed flames are unstable in natural draft configurations due to competing factors between burning velocity and bulk flow velocity, leading to flashback and limited implementation in combustion systems without forced draft devices.
Innovation Solution
A burner apparatus with a burner plate and mesh in the fuel-air mixing chamber, where the mesh is in contact with the burner plate, stabilizes lean premixed flames by increasing the local velocity of the unburned air-fuel mixture and preventing flashback, using a wire mesh with 25% to 75% open area and a thickness of 0.010 inches to 0.030 inches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If lean premixed flames are used in natural draft configuration, then emissions are reduced and efficiency is improved, but flame stability deteriorates leading to flashback
Solution Approach 1:
A mesh screen is introduced as an intermediary element between the fuel-air mixture and the combustion zone. The mesh acts as a physical mediator that stabilizes the flame front, preventing it from propagating upstream into the mixing chamber while still allowing the lean premixed combustion to proceed efficiently at the burner surface.
Solution Approach 2:
The mesh screen utilizes its porous structure with specific open area ratios (25%-75%) to achieve flame stabilization. The porous geometry creates a distributed array of small channels that enhance flame attachment and prevent flashback by increasing the surface area for combustion while maintaining the lean premixed conditions.
2Reliability
If forced draft devices are used to maintain combustion air pressure, then flame stability is improved, but device complexity and cost increase
Solution Approach 1:
The forced draft device is extracted from the system entirely. The invention achieves flame stabilization in natural draft configuration by using the mesh screen to compensate for the absence of positive pressure, allowing the system to operate without mechanical air-moving components while maintaining reliability.
Solution Approach 2:
The natural draft system utilizes the buoyancy of hot combustion gases to drive airflow through the system. The mesh screen is designed to work passively with this natural flow, requiring no external power source or active control mechanisms to stabilize the flame.
3Productivity
If mesh with high open area is used, then fuel-air mixture flow is improved, but flame stability deteriorates
Solution Approach 1:
The mesh parameters (open area, wire diameter, mesh size) are optimized to specific ranges. The open area is maintained between 25%-75% to balance flow and stability, with the specific parameters selected to achieve the desired trade-off between mixture throughput and flame anchoring capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the stability of lean premixed flames, preventing flashback and ensuring reliable operation by maintaining a bulk flow velocity greater than the flame speed, thus expanding the use of natural draft lean premixed burners for low emissions and improved efficiency.
Implementation Method 1
the mesh increases the local velocity of the unburned air-fuel mixture
Implementation Method 2
preventing flashback, using a wire mesh with 25% to 75% open area
Data Source
AI summary
This disclosure provides systems, methods, and apparatus related to burner apparatus for lean premixed flames. In one aspect, an apparatus includes a burner plate, a burner body, and a mesh. A first surface of the burner plate defines a combustion surface for a fuel/air mixture. The burner plate defines a plurality of primary ports. The burner body defines a fuel-air mixing chamber. One surface of the burner body comprises the burner plate. The burner body defines an inlet for receiving air and a fuel in the fuel-air mixing chamber. The mesh is disposed in the fuel-air mixing chamber and is in contact with a second surface of the burner plate.